Marek's disease virus (MDV) is a pathogenic agent capable of inducing cancer in chickens and represents a major obstacle in commercial poultry. Marek's disease (MD) is a lymphoproliferative and neuropathic disease of chickens, caused by a highly contagious, cell-associated, oncogenic herpesvirus called Marek's disease virus (MDV) (Calnek, B. W. (2001) Pathogenesis of Marek's disease virus infection, Curr Top Microbiol Immunol 255, 25-55.). MD was originally described as ‘polyneuritis’ affecting the peripheral nerves in roosters (Marek, J. (1907) Multiple Nervenentziindung (Polyneuritis) bei Hühnern, Dtsch. Tierärztl. Wochenschr 15, 417-421.). In the 1950s visceral forms of the disease referred to as ‘acute lymphomatosis’, was recognized in the USA particularly in broilers (Benton, W. J., and Cover, M. S. (1957) The increased incidence of visceral lymphomatosis in broiler and replacement birds, Avian Dis 1, 320-327.). This form of the disease increased in severity with the rapid expansion of the vertically integrated poultry operations after World War II. In the 1970, prior to use of MDV vaccines, the losses from carcass condemnation of broilers accounted for about $200 millions per annum, representing condemnation of 1.5% of broilers examined. After the introduction of vaccines, the broiler condemnation rates have steadily declined to less than 0.01% today (Witter, R. L. (2001) Protective efficacy of Marek's disease vaccines, Curr Top Microbiol Immunol 255, 57-90.). However, MD still remains an economical important disease because of vaccination breaks and emergence of more virulent strains. While currently employed immunization methods demonstrate some efficacy against the disease, the virus typically persists in chicken houses and continues to evolve, oftentimes breaking through vaccinal immunity. The Meq oncogene, which resides in MDV, represents an attractive target for vaccinal control and prevention of Marek's disease, as deletion of Meq results in total loss of MDV oncogenic potential as provided for in U.S. Pat. No. 7,214,524 to Reddy et al., hereby incorporated by reference. However, previously disclosed Meq deleted vaccines were shown to have variable protection in chickens challenged with highly virulent MDV strains and they appear to cause immunosuppression as seen by immune organ atrophy in vaccinated chickens. Thus, there is a need for improved vaccines directed against Marek's disease in poultry.